Superhydrophic flow control device

ABSTRACT

A wellbore subassembly is provided that includes a device having a production flow path toward a production tubing. The production flow path can include a superhydrophobic coating for restricting the production of an unwanted fluid towards the production tubing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of U.S. patent application Ser. No. 14/398,151,filed Oct. 31, 2014 (allowed), which is a national phase entry under 35USC § 371 of International Patent Application No. PCT/US2013/071703,filed Nov. 25, 2013, the entireties of which are incorporated herein byreference.

TECHNICAL FIELD

The present disclosure relates generally to flow control devices for awellbore and, more particularly (although not necessarily exclusively),to a flow control device having a superhydrophobic surface that canaffect fluid flow.

BACKGROUND

Various devices can be installed in a well traversing ahydrocarbon-bearing subterranean formation. Some devices control theflow rate of fluid between the formation and tubing, such as productionor injection tubing. An example of these devices is a flow controldevice that can control the flow rate of various fluids into the tubing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a well system having helical flowcontrol devices with a functionalized surface that can include asuperhydrophobic material according to one aspect.

FIG. 2 is a perspective view of a helical flow control device positionedaround a tubing string according to one aspect.

FIG. 3 is an end view of the helical flow control device of FIG. 2 thatincludes superhydrophobic material according to one aspect.

FIG. 4 is a cross-sectional view depicting an example of a fluid havinga greater concentration of a wanted fluid contacting an inner wall of ahelical flow control device coated with a superhydrophobic materialaccording to one aspect.

FIG. 5 is a cross-sectional view depicting an example of a fluid havinga greater concentration of an unwanted fluid contacting an inner wall ofa helical flow control device coated with a superhydrophobic materialaccording to one aspect.

FIG. 6 is a side view of an example of a contact angle between a dropletof a liquid and a solid surface with a superhydrophobic materialaccording to one aspect.

FIG. 7 is a cross-sectional view of part of a well system having agravel pack that includes proppants coated with a superhydrophobicmaterial according to one aspect.

DETAILED DESCRIPTION

Certain aspects and features relate to flow control devices with asurface coated with a superhydrophobic material that can control theflow rate of fluid between the formation and tubing. Thesuperhydrophobic material on a surface can change a velocity profile ofa fluid contacting the surface. For example, fluid with a greaterconcentration of a desired or wanted fluid, such as oil, can flow with ahigher velocity along a superhydrophobic-coated surface. Fluid with agreater concentration of an undesired or unwanted fluid, such as naturalgas or water, can flow with a lower velocity along asuperhydrophobic-coated surface.

Flow control devices according to some aspects can include a helicalflow control device having a tubing with an inner surface that is coatedwith a superhydrophobic material. Some fluids, such as oil, can have ahigh surface tension. The high surface tension can increase the contactangle between the superhydrophobic-coated inner surface and oil ascompared to the contact angle between oil and an uncoated inner surfaceof a tubing. The increased contact angle results in less surface contactbetween oil and the superhydrophobic-coated inner surface compared tothe surface contact between oil and an uncoated inner surface. Thedecreased surface contact between the superhydrophobic-coated innersurface and oil can decrease the frictional resistance experienced byoil flowing along the superhydrophobic-coated inner surface. Thevelocity profile of oil flowing along the superhydrophobic-coated innersurface can increase when the frictional drag is decreased. The velocityprofile of a fluid having a greater concentration of oil flowing alongthe superhydrophobic-coated inner surface can also increase as thefrictional drag is decreased. The increase in the velocity profile ofthe fluid having a greater concentration of oil can promote theproduction of that fluid, and thereby oil, through an inner diameter ofthe helical flow control device.

Other fluids can have a lower surface tension than oil. For example,natural gas can have almost no surface tension. The low surface tensionof natural gas can cause a large surface area of natural gas to contactthe superhydrophobic-coated inner surface of the tubing. The largesurface area of contact between natural gas and thesuperhydrophobic-coated inner surface can cause natural gas flowingalong the superhydrophobic-coated inner surface to experience a highfrictional resistance between it and the superhydrophobic-coated innersurface, which can cause the natural gas to experience a higher flowresistivity. The higher flow resistivity can decrease the velocity ofnatural gas flowing across the superhydrophobic-coated inner surface.Fluids having a greater concentration of natural gas can also experiencea decrease in velocity as it flows along the superhydrophobic-coatedinner surface. The lower velocity of the fluid having a greaterconcentration of natural gas can damper or restrict the production ofthe fluid, and thereby natural gas, through the helical flow controldevice.

Other fluids, such as water, can also experience either restriction orpromotion as they flow through the helical flow control device. Forexample, features of the helical flow control device having an innersurface that is coated with a superhydrophobic material can be alteredto restrict the flow of other fluids, such as water. For example, thesize of the tube of the helical flow device can be altered to moregreatly restrict a first type of fluid, such as natural gas, and torestrict less a second type of fluid, such as water or steam.

Flow control devices according to some aspects can include a gravel packassembly with proppants coated with a superhydrophobic material. Somefluids, such as oil, can experience a lower surface area contact withthe superhydrophobic-coated surface of the proppants, compared to thesurface area contact with uncoated proppants. The decrease in thesurface area contact can cause the velocity profile of oil, and fluidhaving a greater concentration of oil, to increase as the fluid passesthrough the coated proppants towards the production tubing. The increasein the velocity of the fluid having a greater concentration of oil canpromote the production of the fluid towards the production tubing.

Other fluids, such as natural gas, can experience an increase infrictional resistance between it and the superhydrophobic-coated surfaceof the proppants, compared to the frictional resistance between it anduncoated proppants. The increase in frictional resistance can cause thevelocity profile of natural gas, and fluids having a greaterconcentration of natural gas, to decrease as the fluids pass through thecoated proppants towards a production tubing. The decrease in thevelocity of fluids having a greater concentration of natural gas candamper the production of the fluids towards a production tubing.

Superhydrophobic material can be a material that repels water at acontact angle that exceeds one hundred and fifty degrees. Superhydrophobia can also be referred to as the Lotus effect.Superhydrophobic material can include nano-composites. Examples ofsuperhydrophobic material can include manganese oxide polystyrene, zincoxide polystyrene, precipitated calcium carbonate, carbon nano-tubestructures, and silica-based nano-coating.

These illustrative examples are given to introduce the reader to thegeneral subject matter discussed here and are not intended to limit thescope of the disclosed concepts. The following sections describe variousadditional embodiments and examples with reference to the drawings inwhich like numerals indicate like elements, and directional descriptionsare used to describe the illustrative embodiments but, like theillustrative embodiments, should not be used to limit the presentinvention.

FIG. 1 depicts a well system 100 having helical flow control devices 114that include superhydrophobic material in an inner wall of the helicalflow control devices 114 according to certain aspects. The well system100 includes a bore that is a wellbore 102 extending through variousearth strata. The wellbore 102 has a substantially vertical section 104and a substantially horizontal section 106. The substantially verticalsection 104 and the substantially horizontal section 106 may include acasing string 108 cemented at an upper portion of the substantiallyvertical section 104. The substantially horizontal section 106 extendsthrough a hydrocarbon bearing subterranean formation 110.

A tubing string 112 extends from the surface into the wellbore 102. Thetubing string 112 can provide a conduit for formation fluids to travelfrom the substantially horizontal section 106 to the surface. Helicalflow control devices 114 and production tubular sections 116 in variousproduction intervals adjacent to the formation 110 are positioned aroundthe tubing string 112. On each side of each production tubular section116 is a packer 118 that can provide a fluid seal between the tubingstring 112 and the wall of the wellbore 102. Each pair of adjacentpackers 118 can define a production interval.

Helical flow control devices 114 can allow for control over the volumeand composition of produced fluids. Formation fluid flowing into aproduction tubular section 116 may include more than one type of fluid,such as natural gas, oil, water, steam and carbon dioxide. “Natural gas”as used herein means a mixture of hydrocarbons (and varying quantitiesof non-hydrocarbons) that exists in a gaseous phase at room temperatureand pressure and in a liquid phase or gaseous phase in a downholeenvironment. Steam and carbon dioxide can be used as injection fluids tocause hydrocarbon fluid to flow toward a production tubular section 116.Natural gas, oil, and water be found in the formation 110.

A helical flow control device 114 according to some embodiments canreduce or restrict production of formation fluid having a greaterconcentration of an unwanted fluid and can promote the production offluid having a greater concentration of a wanted fluid. For example, thehelical flow control devices 114 may autonomously restrict or resistproduction of formation fluid having a greater concentration of unwantedfluid, such as natural gas, water or steam, from a production interval.The helical flow control device 114 can also promote the production offormation fluid having a greater concentration of a wanted fluid, suchas oil, from a production interval. For example, the helical flowcontrol device 114 can include superhydrophobic material on an innerwall that can cause the helical flow control device 114 to promote orrestrict the flow of formation fluid based on one or more properties ofthe formation fluid.

Although FIG. 1 depicts the helical flow control devices 114 positionedin the substantially horizontal section 106, the helical flow controldevices 114 (and production tubular sections 116) can be located,additionally or alternatively, in the substantially vertical section104. Furthermore, any number of the helical flow control devices 114,including one, can be used in the well system 100 generally or in eachproduction interval. In other aspects, the helical flow control devices114 can be positioned in simpler wellbores, such as wellbores havingonly a substantially vertical section. The helical flow control devices114 can be positioned in open hole environments, such as is depicted inFIG. 1, or in cased wells.

FIG. 2 depicts perspective view of a helical flow control device 114positioned around the tubing string 112 according to one aspect. Thehelical flow control device 114 includes tubing 120 having an inner wall122. The inner wall 122 may be any shape, including rectangular. Theinner wall can be coated with a superhydrophobic material. The lengthalong the tubing string 112 that the tubing 120 extends can vary. Forexample, the coils of the tubing 120 that wrap around the tubing string112 can be positioned closely together, so the tubing 120 extends ashort distance along the length of the tubing string 112. In anotherexample, the coils of the tubing 120 can be spaced farther apart, so thetubing 120 extends a greater distance along the length of the tubingstring 112.

FIG. 3 depicts an end view of the helical flow control device 114 ofFIG. 2 that includes a superhydrophobic material 124. The inner wall 122of the tubing 120 of the helical flow control device 114 is coated withthe superhydrophobic material 124. The superhydrophobic material 124 canoverlay the inner wall 122 or be embedded within the inner wall 122. Thesuperhydrophobic material 124 can be on an entire circumferentialportion of the inner wall 122 or on only part of the inner wall 122. Thesuperhydrophobic material 124 can be screen-printed or otherwiseoverlaid on the inner wall 122. In one aspect, the superhydrophobicmaterial 124 is bonded to the inner wall 122 by an adhesive ormechanical coupler. In one aspect, the superhydrophobic material 124 caninclude a nano-structure material that is uniform along the x and y axisof the inner wall 122.

The superhydrophobic material 124 can allow the helical flow controldevice 114 to promote or restrict the flow of fluid based on one or moreproperties of the fluid. For example, the superhydrophobic material 124can increase the contact angle, and thereby decrease the surface areacontact, between the superhydrophobic material 124 and fluid having agreater concentration of oil. The decrease in the surface area contactbetween the fluid having a greater concentration of oil and thesuperhydrophobic material 124 can decrease the frictional dragexperienced by the fluid as it flows across the superhydrophobicmaterial on the inner wall 122. The velocity profile of fluid having agreater concentration of oil as it flows across the superhydrophobicmaterial 124 on the inner wall 122 can increase when the frictional dragis decreased. The increase in the velocity profile of fluid having agreater concentration of oil can promote the production of the fluidthrough the helical flow control device 114 towards a production tubing.

Other fluids, however, can experience a decreased velocity profile whenflowing along the superhydrophobic material 124 on the inner wall 122.For example, natural gas can experience an increase in frictionalresistance when it contacts the superhydrophobic material 124, ascompared to its contact with an uncoated surface. The increase infrictional resistance can decrease the velocity of a fluid having agreater concentration of natural gas flowing across the superhydrophobicmaterial 124 on the inner wall 122. The decreased velocity of the fluidhaving a greater concentration of natural gas flowing along the innerwall 122 can damper the production of the fluid through the helical flowcontrol device 114 towards a production tubing.

Other fluids, such as water, can also experience a decreased velocityprofile when flowing along the superhydrophobic material 124 on theinner wall 122. The superhydrophobic-coated tubing 120 of the helicalflow control device 114 can increase the frictional drag experienced bywater flowing along the inner wall 122 while decreasing the frictionaldrag experienced by oil flowing along the inner wall 122.

In another aspect, additional surfaces that are part of a flow path to aproduction tubing can be coated with a superhydrophobic material. Forexample, sand control screen assemblies can be coated with asuperhydrophobic material.

FIG. 4 depicts a cross-sectional view of an example of a helical flowcontrol device 200 that includes tubing 202 that has asuperhydrophobic-coated inner wall 204 and a fluid 206 having a greaterconcentration of a wanted fluid flowing within an inner diameter of thetubing 202. The fluid 206 that flows within the inner diameter of thetubing 202 can experience a decrease in frictional drag with thesuperhydrophobic-coated inner wall 204. The decrease in frictional dragcan increase the velocity of the fluid 206 along thesuperhydrophobic-coated inner wall 204 of the tubing 202. The increasedvelocity of fluid 206 having a greater concentration of the wanted fluidflowing within the inner diameter of the tubing 202 can promote theproduction of the fluid 206 having a greater concentration of the wantedfluid through the helical flow control device 200 towards a productiontubing. In one aspect, the wanted fluid can be oil.

FIG. 5 depicts a cross-sectional view of a helical flow control device300 that includes tubing 302 that has a superhydrophobic-coated innerwall 304 a fluid 306 having a greater concentration of an unwanted fluidflowing within an inner diameter of the tubing 302. The fluid 306 thatflows within the inner diameter of the tubing 302 has a large surfacearea of contact between it and the superhydrophobic-coated inner wall304. The large surface area of contact can increase the frictionalresistance between the fluid 306 and the superhydrophobic-coated innerwall 304. The increase in frictional resistance can decrease thevelocity of the fluid 306 flowing along the superhydrophobic-coatedinner wall 304 of the tubing 302. The decrease in the velocity of thefluid 306 flowing within the inner diameter of the tubing 302 can damperthe production of the fluid 306 having a greater concentration of theunwanted fluid through the helical flow control device 300 towards aproduction tubing. In one aspect, the unwanted fluid can be one or moreof water, natural gas, or steam.

FIG. 6 depicts a side view of an example of a contact angle between aliquid droplet 400 and a superhydrophobic solid surface 402. The liquiddroplet 400 rests on a superhydrophobic solid surface 402 and issurrounded by a gas 404. The contact angle 406 is formed by the liquiddroplet 400 at the three-phase boundary where the liquid droplet 400,the gas 404, and the solid surface 402 intersect. In one aspect, asuperhydrophobic surface can be defined as a surface in which thecontact angle between the solid surface 402 and a droplet of waterexceeds one hundred and fifty degrees. As the contact angle between theliquid droplet 400 and the solid surface 402 increases, the surface areacontact between the liquid droplet 400 and the solid surface 402decreases.

FIG. 7 depicts a cross-sectional view of part of a well system with aflow control device that includes a gravel pack 502 installed between atubing string 504 and a formation 506. The tubing string 504 can providea conduit for formation fluids to travel from the formation 506 to thesurface. The tubing string 504 also includes additional flow controldevices 507. The gravel pack 502 includes proppants 508. The proppants508 are coated with a superhydrophobic material. The coated proppants508 can allow for control over the volume of produced fluids. Forexample, the coated proppants 508 can autonomously restrict or resistproduction of formation fluid having a greater concentration of unwantedfluid, such as natural gas or water. For example, as formation fluidhaving a greater concentration of natural gas, flows from the formation506 through the coated proppants 508, the formation fluid can experiencean increase in frictional resistance between it and the coated proppants508. The increase in frictional resistance can slow the velocity of theformation fluid through the spaces between the proppants 508 of thegravel pack 502. The decrease in velocity of the formation fluid flowingthrough the gravel pack 502 can limit the amount of formation fluidhaving a greater concentration of natural gas entering the tubing string504 from the formation 506. The formation fluid can enter the tubingstring 504 via the flow control devices 507.

The coated proppants 508 can also autonomously promote the production offluid having a greater concentration of a wanted fluid, such as oil. Asformation fluid having a greater concentration of oil flows from theformation through the coated proppants 508, the formation fluid canexperience a decrease in frictional resistance between it and the coatedproppants 508. The decrease in frictional resistance can increase thevelocity of the formation fluid having a greater concentration of oilthrough the spaces between the proppants 508 of the gravel pack 502. Theincrease in the velocity of the formation fluid as it moves through thegravel pack 502 can increase the amount of formation fluid having agreater concentration of oil entering the tubing string 504 from theformation 506. The formation fluid can enter the tubing string 504 viathe flow control devices 507. In one aspect, the flow control devices507 can be coated with a superhydrophobic material.

The gravel pack 502 can be installed within the wellbore by pumping thecoated proppants 508 downhole along the length of the wellbore. Thecoated proppants 508 can have a decreased frictional resistance betweenthe coated proppants 508 and the wellbore 500 and the tubing string 504.The decrease in friction between the coated proppants 508 and thewellbore 500 and the tubing string 504 can aid in the installation ofthe gravel pack along long intervals within the wellbore.

In one aspect, a wellbore subassembly can include a device having aproduction flow path toward a production tubing. The production flowpath can include a superhydrophobic coating for restricting theproduction of an unwanted fluid towards the production tubing.

In one aspect, a wellbore subassembly can include a tube positionedexternal to a production tubing. The tube can have an inner wall thatincludes a superhydrophobic material for restricting production of anunwanted fluid toward the production tubing.

In another aspect, a wellbore subassembly can include a gravel pack withproppants. The proppants of the gravel back can be positioned between aproduction tubing and a wellbore. The proppants can be coated with asuperhydrophobic material for restricting production of an unwantedfluid toward the production tubing.

The foregoing description of certain aspects, including illustratedaspects, has been presented only for the purpose of illustration anddescription and is not intended to be exhaustive or to limit thedisclosure to the precise forms disclosed. Numerous modifications,adaptations, and uses thereof will be apparent to those skilled in theart without departing from the scope of this disclosure.

What is claimed is:
 1. A wellbore subassembly, comprising: a gravel packcomprising a plurality of proppants positioned between a productiontubing and a wellbore, the plurality of proppants coated with asuperhydrophobic material for restricting production of an unwantedfluid toward the production tubing.
 2. The wellbore subassembly of claim1, wherein the unwanted fluid has a greater concentration of at leastone of water or natural gas than a wanted fluid.
 3. The wellboresubassembly of claim 1, wherein the superhydrophobic material has acontact angle with a water droplet that exceeds one hundred and fiftydegrees.
 4. The wellbore subassembly of claim 1, wherein thesuperhydrophobic material includes at least one of manganese oxidepolystyrene, zinc oxide polystyrene, precipitated calcium carbonate,carbon nano-tube structures, and silica-based nano-coating.
 5. Thewellbore subassembly of claim 1, wherein the superhydrophobic materialis operable for increasing a velocity of fluid having a greaterconcentration of oil flowing through the gravel pack.